Inheritance from multiple interfaces with the same method name

Question

If we have a class that inherits from multiple interfaces, and the interfaces have methods with the same name, how can we implement these methods in my class? How can we specify which method of which interface is implemented?

Answer 1

By implementing the interface explicitly, like this:

public interface ITest {
    void Test();
}
public interface ITest2 {
    void Test();
}
public class Dual : ITest, ITest2
{
    void ITest.Test() {
        Console.WriteLine("ITest.Test");
    }
    void ITest2.Test() {
        Console.WriteLine("ITest2.Test");
    }
}

When using explicit interface implementations, the functions are not public on the class. Therefore in order to access these functions, you have to first cast the object to the interface type, or assign it to a variable declared of the interface type.

var dual = new Dual();
// Call the ITest.Test() function by first assigning to an explicitly typed variable
ITest test = dual;
test.Test();
// Call the ITest2.Test() function by using a type cast.
((ITest2)dual).Test();

Answer 2

You must use explicit interface implementation

Answer 3

You can implement one or both of those interfaces explicitly.

Say that you have these interfaces:

public interface IFoo1
{
    void DoStuff();
}

public interface IFoo2
{
    void DoStuff();
}

You can implement both like this:

public class Foo : IFoo1, IFoo2
{
    void IFoo1.DoStuff() { }

    void IFoo2.DoStuff() { }        
}

Answer 4

Sometimes you may even need to do:

public class Foo : IFoo1, IFoo2
{
    public void IFoo1.DoStuff() { }

    public void IFoo2.DoStuff()
    {
        ((IFoo1)this).DoStuff();
    }        
}

Answer 5

You can implement one interface Explicitly and another implecitely.

public interface ITest {
    void Test();
}
public interface ITest2 {
    void Test();
}
public class Dual : ITest, ITest2
{
    public void Test() {
        Console.WriteLine("ITest.Test");
    }
    void ITest2.Test() {
        Console.WriteLine("ITest2.Test");
    }
}

ITest.Test will be the default implementation.

Dual dual = new Dual();
dual.Test();
((ITest2)dual).Test();

Output:

Console.WriteLine("ITest.Test");
Console.WriteLine("ITest2.Test");

Answer 6

public class ImplementingClass : AClass1, IClass1, IClass2

    {
        public override string Method()
        {
            return "AClass1";
        }
        string IClass1.Method()
        {
            return "IClass1";
        }
         string IClass2.Method()
        {
            return "IClass2";
        }
    }

So when calling from different class you will have to type cast the object into required Interface or Abstract class.

ImplementingClass implementingClass = new ImplementingClass();
((AClass1)implementingClass).Method();

Answer 7

public interface IDemo1
{
 void Test();
}
public interface IDemo2
{
 void Test();
}
public class clsDerived:IDemo1,IDemo2
{
  void IDemo1.Test() 
  {
   Console.WriteLine("IDemo1 Test is fine");
  }
 void IDemo2.Test() 
  {
    Console.WriteLine("IDemo2 Test is fine");
  }
}

public void get_methodes()
{
    IDemo1 obj1 = new clsDerived();
    IDemo2 obj2 = new clsDerived();
    obj1.Test();//Methode of 1st Interface
    obj2.Test();//Methode of 2st Interface
}

Answer 8

Answer is "By using explicit Interface implementation"

Take one example:

using System;

interface A

{
        void Hello();
}

interface B

{
    void Hello();
}


class Test : A, B

{
    void A.Hello()

    {
        Console.WriteLine("Hello to all-A");
    }

    void B.Hello()
    {
        Console.WriteLine("Hello to all-B");

    }

}

public class interfacetest

{
    public static void Main()

    {
        A Obj1 = new Test();

        Obj1.Hello();

        B Obj2 = new Test();

        Obj2.Hello();
    }

}

Output: Hello to all-A Hello to all-B